One form of an all-reflective telescope has a concave primary mirror and a secondary mirror positioned in facing relation to the primary mirror. Incoming light rays are reflected from the primary mirror to the secondary mirror. The secondary mirror reflects the light rays to a detector positioned in the center of the primary mirror.
The secondary mirror is supported in its proper position facing the primary mirror. A conventional approach is to use a “spider”, which in one embodiment is a multi-armed structure extending from the primary mirror to the outer periphery of the secondary mirror. The arms of the spider position the secondary mirror in three dimensions relative to the primary mirror and relative to the detector. The spider has appropriate openings therethrough so that the light rays can reflect from the primary mirror to the secondary mirror, and thence back to the detector.
The conventional spider does provide the required support for the secondary mirror. However, during the development of the present invention, the inventors have identified some disadvantages with the current approach. The assembly of primary mirror, secondary mirror, and spider requires the use of three (or more) high-precision parts, in addition to the detector structure. The three parts must be manufactured and assembled with high precision, and maintained in precise alignment when the telescope is used. These requirements increase the costs associated with fabricating and maintaining the telescope.
There is a need for an improved approach to the construction of the two-mirror telescope, which achieves the required structural support while reducing the complexity and manufacturing, assembly, and alignment difficulties associated with the present approach. The present invention fulfills this need, and further provides related advantages.